U.S. Pat. No. 5,883,303 discloses and describes an apparatus and method for pigging, flooding and pressure testing pipelines utilizing a sliding sleeve valve connected at the end of a pig receiver which automatically opens upon fluid pressure in the pipeline reaching a predetermined limit allowing fluid trapped in the pipeline to escape, and is then automatically closed when the pig enters the pig receiver to allow pressure testing of the pipeline.
U.S. Pat. No. 5,927,901 discloses and describes an underwater pipeline apparatus for delivering a pig unit through an initially air or gas-containing seabed pipeline from an entry point toward an exit point. The apparatus includes an inlet conduit for coupling to a pipeline inlet port at a location behind the pig unit in its intended direction of travel, from the entry point to the exit point, having an opening to the sea to admit pressurized water into the pipeline under the head of water above the pipeline and means to regulate flow of water through the inlet conduit into a pipeline to regulate the speed of delivery of the pig unit along the pipeline.
U.S. Pat. No. 6,109,829 discloses and describes a system for transporting a pig along the interior of a pipeline, particularly for the purpose of installing a liner in the pipeline by towing the liner behind the pig, in which a hydrostatic head is applied on either side of the pig and the head on the downstream side of the pig is reduced such that the pig is transported along the interior of the pipeline by the resultant pressure differential.
The skids of the present invention are moved by and powered by an SV that works at or near the seabead floor. The SV powers the pumps on the skids and eliminates any additional long lengths of power line or cable normally used in prior art methods and apparatus. Also eliminated are the long lengths of coiled tubing, hose, pipe or conduit, and substantial surface support vessel/vessels, all required by the prior art methods. In the dewatering commissioning method, the present invention reduces significantly the volume and required pressure of compressed gas and/or fluids and the size of the pumps, compressors and/or compressor boosters necessary to handle these fluids.